Since you have 2 passengers in 1 PNR, you are likely to get a 2 berth coupe. A lot would depend on what is the passenger list for that day.
For example, if there are say 12 PNRs with 2 passengers each then some will not get 2 berth coupe.
There is no way to opt for a coupe/cabin. it is decided by the guy who does charting.